The long range goal of this laboratory is to determine the function of the immune response (Ir) genes in the regulation of the immune response and in the control of immunocompetent cell interactions. At present the research effort is divided into two main areas: 1) Genetic, serological and physiochemical studies of the antigens of the guinea pig major histocompatibility complex (MHC); 2) The role of the I-region associated (Ia) antigens and Ir gene products in macrophage-T lymphocyte interaction and T lymphocyte antigen recognition. BIBLIOGRAPHIC REFERENCES: Schwartz, B.D., Kask, A.M. and Shevach, E.M. The guinea pig MHC: Functional significance and structural characterization. Cold Spring Harbor Symposia on Quantitative Biology 41: 397-403, 1977. Thomas, D.W. and Shevach, E.M. Nature of the antigenic complex recognized by T lymphocytes. II. T cell activation by direct modification of macrophage histocompatibility antigens. J. Exp. Med. 145: 907-915, 1977.